Placerville climate

Placerville Frost Dates and Growing Season

NOAA 1991-2020 normals for Placerville, 4.4 km from Placerville, elevation 1850 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Placerville. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around March 31 and the first fall freeze around November 21, a growing season of about 237 days.

Median at 36°F
last April 23, first November 6
Median at 32°F
last March 31, first November 21
Median at 28°F
last February 15, first December 5

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 14May 5Apr 30Apr 27Apr 23Apr 20Apr 16Apr 11Apr 6
32°FApr 23Apr 17Apr 11Apr 5Mar 31Mar 22Mar 12Mar 4Feb 24
28°FMar 21Mar 6Feb 28Feb 22Feb 15Feb 8Feb 3Jan 26Jan 14
24°FFeb 21Feb 9Feb 1Jan 24Jan 15Jan 9Jan 3Dec 28Dec 19
20°FJan 30Jan 14Jan 5Dec 31Dec 30Dec 26Dec 21Dec 16Dec 11
16°F–––––––––

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 17Oct 25Oct 30Nov 2Nov 6Nov 10Nov 13Nov 17Nov 22
32°FNov 1Nov 9Nov 14Nov 18Nov 21Nov 25Nov 28Dec 2Dec 7
28°FNov 19Nov 25Nov 29Dec 2Dec 5Dec 9Dec 13Dec 20Jan 1
24°FDec 1Dec 6Dec 11Dec 14Dec 18Dec 27Jan 1Jan 11Jan 28
20°FDec 7Dec 12Dec 16Dec 21Dec 24Dec 29Jan 1Jan 10Jan 25
16°F–––––––––

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F223213206201196192186178166
32°F275263253245237231223216204
28°F330318307301294287279270254
24°F365364355348342336329319307
20°F365365365365365365364353343
16°F365365365365365365365365365

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
82% of years
20°F or colder
31% of years
16°F or colder
4% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
3,176
Cooling degree days, base 65°F
1,300
Growing degree days, base 40°F
7,287
Growing degree days, base 45°F
5,618
Growing degree days, base 50°F
4,181
Growing degree days, base 55°F
3,007
Growing degree days, base 60°F
2,059

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January601019
February470043
March4211109
April3178172
May15267386
June36190605
July2386849
August2349812
September20228659
October14469395
November3902119
December620016

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 4.4 km from Placerville. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00046960 (Placerville). Public domain.